Haemophilia B, an X-linked life threatening bleeding disorder affects 1:30,000 males. Current treatment involves frequent intravenous injections (2-3 times per week) of FIX protein. This treatment is highly effective at arresting bleeding but it is not curative and is extremely expensive (£150,000/patient/year), thus making it unaffordable by the majority of haemophilia B patients in the World. Gene therapy for HB offers the potential for a cure through persistent, endogenous production of FIX following the transfer of a normal copy of the FIX gene to an affected patient. Even a small rise in circulating FIX to ≥1% of normal levels can significantly ameliorate the severe bleeding phenotype.
The inventors have recently successfully piloted a gene therapy approach using adeno-associated viral vectors (AAV) to mediate transfer and expression of the gene for normal coagulation factor IX (FIX) in the liver. Preliminary results of this successful academic, investigator led, trial were published in the New England Journal of Medicine, with experts in the field lauding the work, and calling it a “landmark study”.